The Chemistry of Powder and Explosives - Sciencemadness Dot Org

220 NITRIC ESTERS
Dinitrochlorohydrin (Glycerin chlorohydrin dinitrate)
Among the various substances which may be used in admixture
with nitroglycerin for the purpose of lowering its freezing point,
dinitrochlorohydrin is preferred in Germany but has not found
favor in the United States. Since dinitrochlorohydrin is distinctly
safer to prepare than nitroglycerin, it is most commonly prepared
by itself, that is, by the nitration of chlorohydrin which is substantially
pure and contains not more than a small amount of
glycerin. The product is used directly for the preparation of certain
explosives, or it is mixed with nitroglycerin for the manufacture
of non-freezing dynamites.
Chlorohydrin is prepared by autoclaving glycerin with concentrated
hydrochloric acid or by treating it at moderate temperature
with sulfur chloride. In the former process, in order to
avoid the formation of dichlorohydrin, only enough hydrochloric
acid is used to convert about 75% of the glycerin. The product
is procured by a vacuum distillation. The monochlorohydrin,
which consists almost entirely of the a-compound, comes over
between 130° and 150° at 12-15 mm. and the unchanged glyceria
between 165° and 180°. It is nitrated with the same mixed acid
as is used for the preparation of nitroglycerin; less acid is needed
of course, less heat is produced, and the process is safer and more
rapid.
CH2—OH CH2—Cl CH2—Cl
CH—OH > CH—OH > CH—ONO2
CH2 -OH CH2—OH CHr- ONO2
If a mixture of chlorohydrin and glycerin is nitrated, the resulting
mixture of nitrates contains relatively more nitroglycerin
than the original mixture contained of glycerin, for the relative
increase of molecular weight during the nitration of glycerin is
greater.
Commercial dinitrochlorohydrin is usually yellowish or brownish
in color, specific gravity about 1.541 at 15°. It boils at atmospheric
pressure with decomposition at about 190°. It may be
distilled at 13 mm. at 121.5°, or at 10 mm. at 117.5°, but some
decomposition occurs for the distillate is acid to litmus.
Dinitrochlorohydrin is non-hygroscopic, distinctly more volatile
than nitroglycerin, and it has similar physiological effects. It